The personality trait of Conscientiousness predicts longevity in numerous longitudinal studies: more conscientious people live longer. Explaining this association with a view to developing interventions to enhance health and longevity is now a burgeoning field of personality and health research. The proposed project takes a new approach to this topic, using leukocyte telomere length as the health outcome to be predicted by personality traits. Telomere length is a marker of cellular aging, wherein shorter length indicates greater aging. Unhealthy lifestyle, traumatic life events, and poor physical health are associated with shorter telomere length. Low Conscientiousness is also associated with many of these same variables. The broad aim of the proposed project is to integrate these two separate lines of investigation to study the prospective influence of personality traits, particularly Conscientiousness, on telomere length. More specifically, we will examine whether trait influences on telomere length are mediated by healthy lifestyle, traumatic life events, and physical health indexed by a global measure of health status derived from several biomarkers, and a measure of inflammation indicating oxidative stress (C-reactive protein). To fulfill these aims, the project will use data collected from participants in the Hawaii Longitudinal Study of Personality and Health. The Hawaii sample provides a unique opportunity because of the comprehensive teacher assessments of participants' childhood personality traits at mean age 10, and a rich array of personality, psychosocial, lifestyle, and objective physical health variables obtained subsequently when participants were followed-up at midlife. These include measures of healthy lifestyle (e.g., diet, physical activity, tobacco use); trauma experiences reported for different periods of life, clinical biomarkers of physical health and stored bio-specimens obtained at a baseline exam at age 50. A repeat 10-year follow-up clinical assessment of physical health at age 60 will be underway by the time this project begins. This rare combination of child and adult data enables prospective trait prediction of health outcomes over 40-50 years. At both the baseline and 10 year follow-up clinical assessment, dried blood spots are collected and stored for future analysis. For the proposed research, we will assay leukocyte telomere length using DNA extracted from dried blood collected at the baseline exams for 685 participants, and test models predicting telomere length from the personality traits and potential mediators (Aims 1, 2 and 3). We will also begin to investigate models predicting change in telomere length from baseline (age 50) to follow-up (age 60) on 50 participants (Aim 4). We have already demonstrated the feasibility of our methodology using baseline dried blood spots from the 58 Hawaii Study participants with the highest and lowest levels of childhood Conscientiousness. This proposal builds on our provocative preliminary finding from this pilot work, namely that childhood Conscientiousness at age 10 predicted telomere length at age 50 in this selected group.